diag: Add proper synchronization checks to msg mask table

This fix removes dependency between real time message mask
table and build time message mask table. Also this fix
synchronizes retrieval and modification of real time message
mask table.

CRs-Fixed: 2015227
Change-Id: Id0a0964337ec4645d7061fc35120dfa061a990ff
Signed-off-by: Gopikrishna Mogasati <gmogas@codeaurora.org>